Problem: Simplify the following expression: $y = \dfrac{9a}{6} - \dfrac{5a}{6}$
Since the expressions have the same denominator we simply combine the numerators: $y = \dfrac{9a - (5a)}{6}$ Combine like terms: $y = \dfrac{4a}{6}$ Simplify by dividing numerator and denominator by 2: $y = \dfrac{2a}{3}$